FIRE EFFECTS AND USE
WILDLIFE SPECIES: Ovis canadensis | Bighorn Sheep 



DIRECT FIRE EFFECTS ON ANIMALS : 
Prescribed burning and its associated human activity in bighorn sheep
range may increase stress levels in a population.  Herd condition should
be considered when planning time of fire [27].  No information is
available regarding the direct effects of fire on bighorn sheep.


HABITAT RELATED FIRE EFFECTS : 
Many bighorn sheep populations originally occurred in areas with
frequent fire intervals [19,24].  Bighorn sheep inhabiting the Salmon
River drainage of Idaho occupy a region where over 64 percent of their
habitat has burned since 1900 [24].  

Fire exclusion for over 50 years has allowed plant succession to alter
many bighorn sheep habitats throughout North America [6,7].  Fire
exclusion, which has allowed conifers to establish on grasslands, has
decreased both the forage and security values on many bighorn sheep
ranges [7].

Fire is an important factor in creating habitats that are heavily used
by bighorn sheep [6,27].  Periodic burning keeps seral grasslands from
becoming dominated by coniferous trees [27].  In April 1987, a
prescribed fire was conducted on 235 acres (95 ha) of bighorn sheep
winter range in Custer State Park, South Dakota.  Burning expanded
foraging habitat for bighorn sheep by curtailing encroachment of
pondersosa pine (Pinus ponderosa) onto mixed-grass prairie.  

Burning may regenerate rangelands and enhance the production,
availability, and palatability of important bighorn sheep forage species
[27].  Bighorn sheep heavily utilized burned winter range the following
two winters after a September 1974 fire on the East Fork of the Salmon
River, Idaho [19].  Over 66 percent of the plants on this burned range
had been grazed by bighorn sheep.  Utilization was consistently higher
on burned sites than on adjacent unburned sites for at least 4 years
after the fire [19].
  
Burning can increase visibility for bighorn sheep.  Research has shown
that on burned sites bighorn sheep use areas more distant to escape
terrain than on adjacent unburned sites [27].

Fire can negatively affect bighorn sheep habitat when range condition is
poor and forage species cannot recover, when nonsprouting species that
provide important forage for bighorn sheep are eliminated, or when too
much area is burned and forage is inadequate until the next growing
season.  Another potentially negative effect is when other species,
especially elk, are attracted to prescribed burns intended to benefit
bighorn sheep [19].


FIRE USE : 
Prescribed fire can be useful tool in managing bighorn sheep habitat
[19].  Prescribed burning has been widely used to increase the quantity
and nutritional quality of bighorn sheep forage throughout North America
[7].

Prescribed crown fires conducted in winter in mature conifer stands
adjacent to escape terrain may provide an inexpensive solution to
maintaining or establishing bighorn sheep winter range. In areas where
the available bighorn sheep range is large and provides alternative and
distant wintering sites, fires should be prescribed or located in areas
that would minimize the stress on sheep.  Early spring fires,
particularly on south and southwest aspects, may provide more spring
forage than would otherwise be available for bighorn sheep [27].
Burning immature forests and scrublands adjacent to bighorn sheep winter
range could also provide migration corridors between winter and summer
ranges [24].

Prescribed burning has been used to establish and maintain subalpine
bighorn sheep range in British Columbia.  According to Bentz and Woodard
[2], burning provides an economical method of converting subalpine
forests, which are of low value to bighorn sheep, to earlier seral plant
communities.  On the British Columbia range, bighorn sheep used burned
sites more than adjacent unburned sites.

Since both positive and negative effects can occur from burning bighorn
sheep range, a well-thought-out plan must be developed before fire is
considered for use on their range.  Plans must consider the following:

1) condition of plants
2) plant response to burning
3) adjacent conifers (The possibility of creating more open range exists
   if conifer stands or tall shrub fields occur next to currently used ranges.)
4) limiting factors (factors that may limit bighorn sheep populations
   should be identified, and an evaluation made as to how burning will
   effect these limiting factors)
5) lungworm (lungworm infections can possibly be altered by reducing
   bighorn sheep concentrations; however, if burns are small and
   concentrate bighorn sheep, results could be negative.  If burns disperse
   populations, the effects could be positive)
6) competition from other ungulates attracted to burns [19]


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Ovis canadensis | Bighorn Sheep